Encoder

Component Type: Input

Status: Implemented

Overview

Dawn provides two quadrature encoder IO classes:

encoder (CIOEncoder): Provides basic position tracking.
encoder_index (CIOEncoderIndex): Provides position tracking along with index position and index count information.

These components interface with the underlying OS quadrature encoder driver to provide rotation or linear position data to the framework.

Implementation

Both encoder classes use the DTYPE_INT32 data type for position values. They interact with the OS through the porting layer (dawn/include/dawn/porting/encoder.hxx).

CIOEncoder returns a single int32_t value representing the current position.
CIOEncoderIndex returns a vector of three int32_t values: 1. Current position 2. Last index position 3. Index event counter

Both classes support the CMD_RESET trigger to reset the hardware encoder count.

Configuration

Kconfig

CONFIG_DAWN_IO_ENCODER: Enables the basic encoder IO class.
CONFIG_DAWN_IO_ENCODER_INDEX: Enables the index-aware encoder IO class.

YAML

Example configuration for a basic encoder:

ios:
  - id: rot_enc
    type: encoder
    dtype: int32
    config:
      devno: 0
      posmax: 1024

Example configuration for an encoder with index support:

ios:
  - id: spindle_enc
    type: encoder_index
    dtype: int32
    config:
      devno: 1
      posmax: 4096

Supported config fields:

devno: Driver device number (e.g., 0 for /dev/qenc0).
posmax: (Optional) Maximum position value before wrap-around.